Sensor mounting structure, fixing device, and image forming apparatus therewith

ABSTRACT

A sensor mounting structure includes a positioning member, a holding member, and a biasing member. The positioning member is a mounting reference of a sensor. The holding member is attachable to and detachable from the positioning member so as to form a space in which the sensor is disposed with respect to the positioning member. The biasing member includes an arched part which is overhung between a pair of engaging parts engaging with the holding member. The biasing member, while the holding member is attached to the positioning member, elastically deforms the arched part that is sandwiched between the holding member and the sensor that is disposed in the space so as to bias the sensor to the positioning member.

INCORPORATION BY REFERENCE

This application is based on and claims the benefit of priority fromJapanese Patent application No. 2017-003167 filed on Jan. 12, 2017, theentire contents of which are incorporated herein by reference.

The present disclosure relates to a sensor mounting structure, a fixingdevice, and an image forming apparatus therewith.

In an electronic device such as an image forming apparatus, a variety ofsensors to detect a device state or the like are provided.

For example, there is proposed a structure of mounting an opticalmeasuring sensor to an optical device via a plate spring obtained bycontinuously forming two left and right bent part to each other in asubstantial S-shape. A bent part at the right side of the plate springsandwiches a sensor holder, a visual sensitivity filter, and an opticalmeasuring sensor. A bent part at the left side of the plate spring isfixed to be inserted into a main body mounting part. In this structure,the sensor holder that has held the visual sensitivity filter and theoptical measuring sensor thereon is pressed against the main bodymounting part by a biasing force (spring pressure) of the plate spring.

SUMMARY

In accordance with an aspect of the present disclosure, a sensormounting structure includes a positioning member, a holding member, anda biasing member. The positioning member is a mounting reference of asensor. The holding member is attachable to and detachable from thepositioning member so as to form a space in which the sensor is disposedwith respect to the positioning member. The biasing member includes anarched part which is overhung between a pair of engaging parts engagingwith the holding member. The biasing member, while the holding member isattached to the positioning member, elastically deforms the arched partthat is sandwiched between the holding member and the sensor that isdisposed in the space so as to bias the sensor to the positioningmember.

In accordance with an aspect of the present disclosure, a fixing deviceincludes a fixing member, a pressing member, and the sensor mountingstructure. The fixing member heats, while rotating, a toner image on amedium. The pressing member forms, while rotating, a nip with respect tothe fixing member and then presses the medium passing through the nip.The sensor mounting structure mounts the sensor configured to detect atemperature of the fixing member.

In accordance with an aspect of the present disclosure, an image formingapparatus includes the fixing device.

The above and other objects, features, and advantages of the presentdisclosure will become more apparent from the following description whentaken in conjunction with the accompanying drawings in which a preferredembodiment of the present disclosure is shown by way of illustrativeexample.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view schematically showing an internal structureof a color printer according to a first embodiment of the presentdisclosure.

FIG. 2 is a sectional view schematically showing a fixing deviceaccording to the first embodiment of the present disclosure.

FIG. 3 is a sectional view schematically showing a fixing roller and asensor mounting structure of the fixing device according to the firstembodiment of the present disclosure.

FIG. 4 is a perspective view showing the sensor mounting structureaccording to the first embodiment of the present disclosure.

FIG. 5 is a perspective view showing a holding member and a biasingmember of the sensor mounting structure according to the firstembodiment of the present disclosure.

FIG. 6 is a perspective view showing the biasing member of the sensormounting structure according to the first embodiment of the presentdisclosure.

FIG. 7 is a perspective view showing, from a front side, the biasingmember of the sensor mounting structure according to the firstembodiment of the present disclosure.

FIG. 8 is a sectional view showing an assembling course of the sensormounting structure according to the first embodiment of the presentdisclosure.

FIG. 9 is a sectional view showing the sensor mounting structureaccording to the first embodiment of the present disclosure.

FIG. 10 is a perspective view showing a biasing member of a sensormounting structure according to a second embodiment of the presentdisclosure.

FIG. 11 is a perspective view showing a biasing member of a sensormounting structure according to a third embodiment of the presentdisclosure.

FIG. 12 is a perspective view showing a biasing member of a sensormounting structure according to a fourth embodiment of the presentdisclosure.

FIG. 13 is a perspective view showing a biasing member of a sensormounting structure according to a modification example of the fourthembodiment of the present disclosure.

FIG. 14 is a perspective view showing a biasing member of a sensormounting structure according to another modification example of thefourth embodiment of the present disclosure

FIG. 15 is a perspective view showing a biasing member of a sensormounting structure according to a fifth embodiment of the presentdisclosure.

FIG. 16 is a perspective view showing a biasing member of a sensormounting structure according to a sixth embodiment of the presentdisclosure.

DETAILED DESCRIPTION

Hereinafter, with reference to accompanying figures, embodiments of thepresent disclosure will be described. A near side of figures such asFIG. 1 will be set as a front side. Arrows Fr, Rr, L, R, U, and D shownin the figures indicate a front side, a rear side, a left side, a rightside, an upside, and a downside, respectively.

First Embodiment

Entire Configuration of Color Printer

With reference to FIG. 1, an entire configuration of a color printer 1as an example of an image forming apparatus will be described. FIG. 1 isa sectional view schematically showing an internal structure of thecolor printer 1.

The color printer 1 includes a main body 2 configurating a substantiallyrectangular parallelepiped-shaped appearance. In a lower part of themain body 2, a sheet feeding cartridge 3 storing (a stack of) papersheets S is attachably and detachably provided. In an upper surface ofthe main body 2, an ejected sheet tray 4 is provided. The sheet S, whichis an example of a medium, is not limited to the paper sheet and can bea resin sheet or the like.

The color printer 1 includes a sheet feeding device 5, an imaging device6, and a fixing device 7 in the main body 2. The sheet feeding device 5is provided at an upstream end of a conveying path 8 extending from thesheet feeding cartridge 3 to the ejected sheet tray 4. The fixing device7 is provided at a downstream side of the conveying path 8, and theimaging device 6 is provided on the conveying path 8 and between thesheet feeding device 5 and the fixing device 7.

The imaging device 6 includes four toner containers 10, an intermediatetransferring belt 11, four drum units 12, and an optical scanning device13. The four toner containers 10 respectively store four colors (yellow,magenta, cyan, and black) of toners (developers). The intermediatetransferring belt 11 rotates in a counterclockwise direction of FIG. 1.Each drum unit 12 includes a photosensitive drum 14, a charger 15, adevelopment device 16, a first transfer roller 17, and a cleaning device18. Each first transfer roller 17 is provided so as to interpose theintermediate transfer belt 11 between the first transfer roller 17itself and the corresponding photosensitive drum 14. A second transferroller 19 is in contact with a right side of the intermediate transferbelt 11 so as to form a transferring nip N1.

The color printer 1 forms an image on a sheet S according to followingprocedures. Each charger 15 charges a surface of the correspondingphotosensitive drum 14. Each photosensitive drum 14 receives a scanninglight emitted from the optical scanning device 13 and carries anelectrostatic latent image. Each development device 16 develops thecorresponding electrostatic latent image to forma toner image using thetoner supplied from the corresponding toner container 10. Each firsttransfer roller 17 primarily transfers the corresponding toner image onthe corresponding photosensitive drum 14 to the rotating intermediatetransfer belt 11. The intermediate transfer belt 11, while rotating,carries a full-color toner image in which the four-colored toner imagesare overlapped. The sheet S is fed out by the sheet feeding device 5from the sheet feeding cartridge 3 to the conveying path 8. The secondtransfer roller 19 secondarily transfers the toner image having beenformed on the intermediate transfer belt 11 to the sheet S passingthrough the transferring nip N1. The fixing device 7 thermally fixes thetoner image on the sheet S. Afterward, the sheet S is ejected to theejected sheet tray 4. Each cleaning device 18 removes the tonerremaining on the corresponding photosensitive drum 14.

<Fixing Device>

With reference to FIG. 2 and FIG. 3, the fixing device 7 will bedescribed. FIG. 2 is a sectional view schematically showing the fixingdevice 7. FIG. 3 is a sectional view schematically showing a fixingroller 31 and a sensor mounting structure 34 of the fixing device 7.

As shown in FIG. 2 and FIG. 3, the fixing device 7 includes a fixingroller 31, a pressing roller 32, a heating unit 33, and the sensormounting structure 34. The fixing roller 31 and the pressing roller 32are cylindrical members which are elongated in a longitudinal direction(axial direction), respectively. The heating unit 33 is a device forheating the fixing roller 31. The sensor mounting structure 34 is astructure for mounting a temperature sensor 35 which detects atemperature of the fixing roller 31.

As shown in FIG. 2, the fixing roller 31 as an example of a fixingmember includes: a fixing elastic layer 31B which has been laminated onan outer circumferential face of a metallic fixing cored bar 31A; and afixing belt 31C which covers the fixing elastic layer 31B. Both ends inthe longitudinal direction of the fixing cored bar 31A are supported tobe rotatable by a pair of metal plates 36 (refer to FIG. 3). Thepressing roller 32 as an example of a pressing member includes: apressing elastic layer 32B which has been laminated on an outercircumferential face of a pressing cored bar 32A; and a pressing releaselayer 32C which covers the pressing elastic layer 32B. Both ends in thelongitudinal direction of the pressing cored bar 32A are supported to berotatable by a pair of movable metal plates (not shown). The pressingroller 32 is pressed against the fixing roller 31 while being biased byeach movable metal plate by way of a spring (not shown). The pressingroller 32 forms a fixing nip N2 together with the fixing roller 31.

The heating unit 33, while the fixing roller 31 is sandwiched, isprovided at an opposite side of the fixing nip N2. The heating unit 33includes a plurality of IH coils 33B which have been supported by asubstantially semi-cylindrical holder 33A. The plurality of IH coils 33Bare covered with an arched core 33C which has been formed of aferromagnetic body such as a ferrite.

Here, functions of the fixing device 7 will be described. The pressingroller 32 is connected to a motor or the like (not shown) via a geartrain or the like and then rotates while receiving a driving force ofthe motor. The fixing roller 31 is sequentially driven by the pressingroller 32 and then rotates along a shaft. Each IH coil 33B, whilereceiving supply of power from a power source (not shown), generates ahigh frequency magnetic field and then heats the fixing belt 31C. Thefixing roller 31, while rotating around the shaft, heats a toner imageon a sheet S passing through the fixing nip N2. The pressing roller 32,while rotating around the shaft, presses the sheet S passing through thefixing nip N2. Afterwards, the toner image is fixed to the sheet S.Although in the embodiment, the pressing roller 32 is driven to rotate,it may be that the fixing roller 31 is driven to rotate, and thepressing roller 32 is sequentially driven to rotate, without beinglimitative thereto.

As shown in FIG. 3, in the fixing device 7, a temperature sensor 35which detects a temperature of the fixing roller 31 (fixing belt 31C) isprovided. The temperature sensor 35 is disposed to oppose to the fixingroller 31 in the vicinity of a center in the longitudinal direction ofthe fixing roller 31. The temperature sensor 35 is a radiationthermometer which optically receives an infrared ray which has beenradiated from the fixing roller 31 in a noncontact manner and thenconverts the amount of light reception to a temperature, for example.The temperature sensor 35 is electrically connected to a control device37 which controls image forming operation (refer to FIG. 2). The controldevice 37, in the case of having determined that the temperaturemeasured by the temperature sensor 35 indicates excessive heating of thefixing roller 3 l, stops supply of power to the heating unit 33 (each IHcoil 33B). In this manner, an excessive temperature rise of the fixingroller 31 can be restrained.

The temperature sensor 35 of a noncontact type needs to be positionedwith a high accuracy so as to constantly keep a distance from the fixingroller 31, since a measurement range thereof is determined depending ona distance from the fixing roller 31. Therefore, the fixing device 7according to the first embodiment includes the sensor mounting structure34 for easily carrying out highly accurate positioning of thetemperature sensor 35.

<Sensor Mounting Structure>

With reference to FIG. 3 to FIG. 7, the sensor mounting structure 34will be described. FIG. 4 is a perspective view showing the sensormounting structure 34. FIG. 5 is a perspective view showing a holdingmember 41 and a biasing member 42 of the sensor mounting structure 34.FIG. 6 is a perspective view showing the biasing member 42. FIG. 7 is aperspective view showing the biasing member 42 from a front side.

As shown in FIG. 3, the sensor mounting structure 34 includes apositioning metal plate 40, the holding member 41, and the biasingmember 42. The positioning metal plate 40 as an example of a positingmember is a member serving as amounting reference of the temperaturesensor 35 as well. The holding member 41 is provided to be attachable toand detachable from the positioning metal plate 40. The biasing member42 is attached to the holding member 41.

The positioning metal plate 40 is overhung between a pair oflongitudinal metal plates 36 at a lower side than the fixing roller 31.The positioning metal plate 40 is made of a metal material, for example,and is formed in a substantially plate-like shape. The positioning metalplate 40 is disposed to be substantially in parallel to the fixingroller 31, and a top face thereof forms a substantially horizontal face.

As shown in FIG. 4, in the vicinity of a center in the longitudinaldirection of the positioning metal plate 40, a positioning hole 40A forexposing a light reception part 35A of the temperature sensor 35 opens.The positioning hole 40A is formed in a substantially rectangular shapeas seen from a plane. In addition, at the positioning metal plate 40, apair of hook engaging holes 40B open while being spaced from each otherin the longitudinal direction. A front hook engaging hole 40B is formedso as to cut out a front end of the positioning hole 40A towards thefront side. Namely, the front hook engaging hole 40B is formedintegrally with the positioning hole 40A. A rear hook engaging hole 40Bis formed at a position which is distant more rearward than that of thepositioning hole 40A. Each hook engaging hole 40B is formed in asubstantially rectangular shape as seen from a plane.

As shown in FIG. 5, the holding member 41 is made of a synthetic resinmaterial, for example, and is formed in a substantially plate-like shapewhich is elongated in the longitudinal direction. At the holding member41, a pair of engaging protrusions 41A are formed to be spaced from eachother in the longitudinal direction. Around the pair of engagingprotrusions 41A, a spring engaging hole 41B formed in a substantialU-shape opens. In other words, the pair of engaging protrusions 41A areformed while extending in a direction in which these protrusions arespaced from each other from an edge at which the pair of spring engagingholes 41B oppose to each other. A rear engaging protrusion 41A is formedto be elongated more significantly in the longitudinal direction and tobe thicker in the vertical direction than a front engaging protrusion41A (refer to FIG. 8).

In addition, as shown in FIG. 4 and FIG. 5, in the holding member 41, apair of hooking parts 41C are formed to be spaced from each other so asto sandwich the pair of engaging protrusions 41A between both sides inthe longitudinal direction. Each hooking part 41C is formed in asubstantial L-shape while a tip end thereof extending upward from a topface of the holding member 41 is bent to a front side. A return partprotrudes on a bottom face of a tip end of each hooking part 41C.Although later described in detail, the pair of hooking parts 41C engagewith the pair of hook engaging holes 40B, and the holding member 41 isthereby attached to the positioning metal plate 40.

As shown in FIG. 6 and FIG. 7, the biasing member 42 is formed in theshape of an elongated ring in the longitudinal direction by bending ametallic wire rod, for example. The biasing member 42 includes a pair ofarched parts 60 which are overhung between a pair of engaging parts 50which engage with the holding member 41.

The pair of engaging parts 50 are disposed to be spaced from each otherin the longitudinal direction. The pair of engaging parts 50 extenddownward from both ends in the longitudinal direction (overhangingdirection) of the pair of arched parts 60. The pair of engaging parts 50each are formed in a substantial U-shape which is bent so as to overhangon the engaging protrusion 41A. In more detail, each engaging part 50 isformed in a substantially rectangular shape (substantial U-shape) by: apair of longitudinal lines 40A extending substantially verticallydownward from the pair of arched parts 60; and a transverse line 50Bextending in a substantially horizontal direction so as to connect alower end of the pair of longitudinal lines 50A thereto. Although thepair of engaging parts 50 are of the substantially same size and areformed in the substantially same shape, the longitudinal line 50B of therear engaging part 50 is cut, and constitutes a pair of cut ends 50C.The pair of cut ends 50 extend in a transverse direction so as tooverlap in parallel to each other.

The pair of arched parts 60 each are formed in a substantially archedshape (substantially archery shape) which protrudes to an upper side.The pair of arched parts 60 are provided to be arranged substantially inparallel to the transverse direction (widthwise direction). The pair ofarched parts 60 are formed in the same shape, and therefore,hereinafter, a single arched part 60 will be described.

The arched part 60 includes a pair of supporting lines 60A, a contactline 60B, and a pair of inclination lines 60C. The pair of support lines60A are provided while extending in the longitudinal direction so thatthe support lines approach each other from the longitudinal lines 50A ofthe pair of engaging parts 50. The contact line 60B is positioned at anupper side than the pair of supporting lines 60A (pressing direction),and is provided while extending in the longitudinal direction betweenthe pair of supporting lines 60A. The pair of inclination lines 60Cconnect the pair of supporting lines 60A and the contact line 60B. Eachinclination line 60C bends obliquely upward via a bent part B1 betweenthe respective supporting lines 60A, and bends obliquely downward via abent part B2 with respect to the contact line 60B. Namely, the pair ofinclination lines 60C incline upward from the outside towards the insidein the longitudinal direction. Therefore, the arched part 60 is formedin a substantially trapezoidal shape as seen from a lateral side.

Next, with reference to FIG. 5, FIG. 8, and FIG. 9, an assemblingprocedure of the sensor mounting structure 34 (positioning procedure ofthe temperature sensor 35) will be described. FIG. 8 is a sectional viewshowing the assembling course of the sensor mounting structure 34. FIG.9 is a sectional view showing the sensor mounting structure 34.

First, as shown in FIG. 5, a worker mounts the biasing member 42 to theholding member 41. For example, the worker hooks the front engaging part50 of the biasing member 42 on the front protrusion 41A that has beenformed in the holding member 41. Subsequently, the worker, whilerearward pulling and stretching the biasing member 42, hooks the rearengaging part 50 on the rear engaging protrusion 41A. In the manner asdescribed above, the biasing member 42 is in a state of being mounted tothe holding member 41 via the pair of engaging parts 50 (refer to FIG. 8as well). The worker may hook the front engaging part 50 on the engagingprotrusion 41A after having hooked the rear engaging part 50 on theengaging protrusion 41A.

Next, as shown in FIG. 8, the worker places the temperature sensor 35 ina posture in which the light reception part 35A has been oriented to anupper side on the biasing member 42 (the pair of arched parts 60) thathas been mounted to the holding member 41 and thereafter mounts theholding member 41 to a lower side of the positioning metal plate 40.Specifically, the worker passes the front part 41C of the holding member41 from a lower side to an upper side with respect to the front hookengaging hole 40B that has been formed in the positioning metal plate 40and then hooks the hooking part 41C on a front side edge of the hookengaging hole 40B (refer to FIG. 9).

Subsequently, the worker upward turns a rear part of the holding member41 while a contact part between the hooking part 41C and the hookengaging hole 40B is employed as a supporting point. Afterwards, thelight reception part 35A of the temperature sensor 35 passes through thepositioning hole 40A from the lower side to the upper side, and a partother than the light reception part 35A of the temperature sensor 35comes into contact with a bottom face of the positioning metal plate 40(refer to FIG. 9).

When turning of the holding member 41 advances, the temperature sensor35 moves relatively downward and thus the pair of arched parts 60 (eachinclination line 60C) is pressed to the holding member 41 side and thenelastically deforms. That is, in more detail, bent parts B1, B2 of eacharched part 60 (refer to FIG. 6) slacken and then each inclination line60C elastically deforms so as to be substantially in parallel to thecontact line 60B (each supporting line 60A) (refer to FIG. 9).Concurrently with elastic deformation of each arched part 60, an entirelength of the biasing member 42 slightly extends in the longitudinaldirection.

When turning of the holding member 41 further advances, the rear hookingpart 41C of the holding member 41 comes into contact with the bottomface of the positioning metal plate 40. The worker, while rearwardslackening the rear hooking part 41C, inserts it into the rear hookengaging hole 40B. Afterwards, as shown in FIG. 9, the rear hooking part41C passes through the rear hook engaging hole 40B and is then hooked ona front side edge thereof. In the manner as described above, assemblingof the sensor mounting structure 34 (positioning of the temperaturesensor 35) completes. The holding member 41 may be fixed to thepositioning metal plate 40 by a fixing member such as a screw so as tomaintain the state in which the holding member has been hooked on thepositioning metal plate 40.

The holding member 41 is mounted to the positioning metal plate 40 so asto form a space in which the temperature sensor 35 is disposed withrespect to the positioning metal plate 40. In addition, the biasingmember 42, while the holding member 41 is attached to the positioningmetal plate 40, elastically deforms the pair of arched parts 60 that hasbeen sandwiched between the holding member 41 and the temperature sensor35 that has been disposed in the space so as to bias the temperature 35towards the positioning metal plate 40. In more detail, the biasingmember 42 brings each supporting line 60A into contact with a top faceof the holding member 41 and brings the contact line 60B into contactwith a bottom face of the temperature sensor 35 and then biases theholding member 41 and the temperature sensor 35 in a state in which theyare spaced from each other by a resilient force of each inclination line60C. In actual, each contact line 60B slackens slightly downward at anintermediate part in the longitudinal direction and thus four bent partsB2 between each inclination line 30C and the contact line 60B (refer toFIG. 6) come into contact with the bottom face of the temperature sensor35. Namely, the temperature sensor 35 is biased upward while beingsupported by the biasing member 42 at substantially four points.

The sensor mounting structure 34 according to the first embodiment asdescribed hereinabove is configured in such a manner that the biasingmember 42 is mounted to the holding member 1 via the pair of engagingparts 50. In addition, the above structure is configured in such amanner that the holding member 41 having mounted the biasing member 41thereto is attached to the positioning metal plate 40, and thetemperature sensor 35 having been disposed between the positioning metalplate 40 and the holding member 41 is thereby biased towards the pair ofarched part 60 and then is pressed against the positioning metal plate40. With this configuration, the temperature sensor 35 can be fixed tothe positioning metal plate 40 merely by carrying out a simple work ofattaching the holding member 41 that has mounted the biasing member 42to the positioning metal plate 40. In this manner, a distance betweenthe fixing roller 31 and the temperature sensor 35 can be kept constant.Namely, positioning of the temperature sensor 35 can be easily andaccurately carried out. With the configuration of the embodiment, thefixing device 7 having the sensor mounting structure that achieves thetechnical effects as described above and the image forming apparatus 1having the fixing device 7 are provided.

In addition, with the sensor mounting structure 34 according to thefirst embodiment, an annular biasing member 42 can be less expensivelymanufactured by applying a bending process or the like to a wire rod.Further, the pair of engaging parts 50 are hooked on the pair ofengaging protrusions 41A to be thereby able to easily mount the biasingmember 42 to the holding member 41. In this manner, the assembling workof the sensor mounting structure 34 can be easily carried out.

Second Embodiment

Next, with reference to FIG. 10, a sensor mounting structure 34 (biasingmember 43) according to a second embodiment will be described. FIG. 10is a perspective view showing the biasing member 43. In the followingdescription, like constituent elements of the sensor mounting structure34 according to the first embodiment are designated by like referencenumerals, and a duplicate description thereof is omitted (this alsoapplies to other embodiments which will be described later).

The biasing member 43 has engaging parts 50, 51 which are longitudinallydifferent from each other. The cut rear engaging part 51 is formed to benarrower in a transverse direction (widthwise direction) than the frontengaging part 50 that is not cut (that is, continuous). Therefore, anoverlap width of a pair of cut ends 50C becomes large. In addition, agap (transverse gap) between a pair of arched parts 60 is graduallynarrower from a front side towards a rear side.

In the sensor mounting structure 34 (biasing member 43) according to thesecond embodiment as described hereinabove, the rear engaging part 51sandwiches the engaging protrusion 41A while being overhung on the rearengaging protrusion 41A that is formed in the holding member 41 (referto FIG. 8 or the like). With this configuration, slippage of the biasingmember 43 that is mounted to the holding member 41 can be prevented, andthe biasing member 43 with respect to the holding member 41 can be held.

Third Embodiment

Next, with reference to FIG. 11, a sensor mounting structure 34 (biasingmember 44) according to a third embodiment will be described. FIG. 11 isa perspective view showing the biasing member 44.

The biasing member 44 includes a pair of cut ends 52C extending in atransverse direction (widthwise direction) so that cut rear engagingparts 52 cross each other. The pair of cut ends 52C each inclineobliquely upward from a proximal end (longitudinal line 50A side)towards an end face side (free end side). That is, the pair of cut ends52C each incline so as to relatively bias the engaging protrusion 41Aupward (in the pressing direction) while the rear engaging part 52 ishooked on the engaging protrusion 41A (refer to FIG. 8 or the like).Therefore, the rear engaging part 52 tightens the engaging protrusion41A while being overhung on the rear engaging protrusion 41A that hasbeen formed in the holding member 41.

In addition, the biasing member 44 inclines to the inside in atransverse direction so that a pair of arched parts 61 approach eachother towards an upper side. Inclination (inclination angle θ) of eacharched part 61 is set in a range of 5 degrees to 10 degrees (5 degreesor more and 10 degrees or less) with respect to a vertical line that hasbeen extended vertically upward from a longitudinal line 50A that isconnected to the arched part 61.

In the course in which the holding member 41 mounted to the biasingmember 44 is attached to the positioning metal plate 40, the pair ofarched parts 61 are pressed against a temperature sensor 35 whichrelatively lowers and then elastically deformed downward while twistingso that these arched parts approach each other. The pair of arched parts61 inward twist each other and thus the pair of cut ends 52C turn so asto extend in the transverse direction (refer to the arrow of FIG. 11).Therefore, the pair of cut ends 52C deform from a posture in which thesecut ends have inclined so as to cross each other to a posture in whichthey are formed in parallel to each other. Afterwards, tightening of theengaging protrusion 41A by the rear engaging part 52 is released. On theother hand, the pair of arched parts 61 elastically deform while inwardtwisting each other and then presses the temperature sensor 35 againstthe positioning metal plate 40.

In the sensor mounting structure 34 (biasing member 44) according to thethird embodiment as described hereinabove, the cut rear engaging part 52(pair of cut ends 52C) is configured to tighten the engaging protrusion41A. With this configuration, slippage of the biasing member 44 that hasbeen mounted to the holding member 41 can be prevented. In addition, thepair of arched parts 61, while the holding member 41 is attached to thepositioning metal plate 40, are pressed relatively against thetemperature sensor 35 and then twist so that the arched parts furtherapproach each other to thereby decrease a biasing force of the pair ofcut ends 52C with respect to the engaging protrusion 41A. With thisconfiguration, tightening of the engaging protrusion 41A by the rearengaging part 52 is released, so that the pair of arched parts 61 canelastically deform substantially uniformly all over the longitudinaldirection. In this manner, the temperature sensor 35 can be pressedagainst the positioning metal plate 40 by an appropriate biasing force.

Fourth Embodiment

Next, with reference to FIG. 12, a sensor mounting structure 34 (biasingmember 45) according to a fourth embodiment will be described. FIG. 12is a perspective view showing the biasing member 45.

An arched part 62 of the biasing member 45 includes an elastic part 70which elastically deforms in a longitudinal direction (overhangingdirection). Namely, the biasing member 45 is configured to expand orcontract in the longitudinal direction. A pair of elastic parts 70 areformed in the arched part 62 in place of a contact line 60B. Eachelastic part 70 is formed while a return part 70A in a substantialU-shape, which has been returned in a transverse direction as seen froma plane, is made continuous in the longitudinal direction. Namely, eachelastic part 70 is formed so as to meander in the transverse directionon a horizontal plane.

With the sensor mounting structure 34 (biasing member 45) according tothe fourth embodiment as described hereinabove, each elastic part 70 canbe pulled and stretched in the longitudinal direction, so that thebiasing member 45 can be easily mounted to a holding member 41. Thecharacterizing features of the biasing member 45 described above may beapplied to the biasing members 43, 44 according to the second or thirdembodiment.

In addition, although the biasing member 45 described above is formed inthe shape meandering on the horizontal plane, the present disclosure isnot limitative thereto. For example, as shown in FIG. 13, as a biasingmember 45 according to a modification example of the fourth embodiment,each elastic part 71 may be formed to bend towards a part of each archedpart 62 (for example, in the vicinity of a center in the longitudinaldirection of the contact line 60B) in a substantial U-shape (downwardprotrusive shape). In addition, for example, as shown in FIG. 14, as abiasing member 45B according to another modification example of thefourth embodiment, each elastic part 72 may be formed in the shape of acoil spring by spirally bending a part of each arched part 62 (forexample, in the vicinity of the center in the longitudinal direction ofthe contact line 60B). In a case where the biasing members 45A, 45Bdescribed above are employed, it is preferable that a release hole (notshown) for releasing the elastic parts 71, 72 be formed while thebiasing members 45A, 45B are mounted to the holding member 41. Inaddition, any one of the elastic members 70 to 72 may be formed in onearched part 62.

Fifth Embodiment

Next, with reference to FIG. 15, a sensor mounting structure 34 (biasingmember 46) according to a fifth embodiment will be described. FIG. 15 isa perspective view showing the biasing member 46.

The biasing member 46 includes a pair of restraining parts 80 whichsupports a temperature sensor 3 disposed on an arched part 63 so as tohold the sensor. The pair of restraining parts 80 are formed integrallywith each arched part 63. The pair of restraining parts 80 each areformed in a substantial U-shape protruding towards the outside in thetransverse direction from a contact line 60B of the pair of arched parts63 as seen from a plane. Each restraining part 80 is formed in asubstantial L-shape while a tip end thereof extending substantiallyhorizontally from the contact line 60B is bent upward as seen from afront side. The temperature sensor 35 is disposed between the pair ofrestraining parts 80.

With the sensor mounting structure 34 (biasing member 46) according tothe fifth embodiment as described hereinabove, the pair of restrainingparts 80 hold the temperature sensor 35 to be thus able to restrainmovement of the temperature sensor 35 on the plane (in the longitudinalor transverse direction) due to vibration which is generated by rotationor the like of the respective rollers 31, 32. In addition, eachrestraining part 80 elastically deforms, and vibration of thetemperature sensor 35 can be absorbed. In this manner, the temperaturesensor 35 can be protected. The features of the biasing member 46described above may be applied to any one of the biasing members 43 to45 according to the second to fourth embodiments.

Sixth Embodiment

Next, with reference to FIG. 16, a sensor mounting structure 34 (biasingmember 47) according to a sixth embodiment will be described. FIG. 16 isa perspective view showing the biasing member 47.

An arched part 64 of the biasing member 47 includes four contact parts90 which come into contact with a temperature sensor 35. The fourcontact parts 90 are formed in a bent part B2 between each inclined part60C and a contact line 60B. The four contact parts 90 are disposed at apair of arched parts 64 so as to form apexes of a rectangle as seen froma plane. That is, the four contact parts 90 are disposed so that linesconnecting the respective contact parts 90 constitute a plane(rectangle). Each contact part 90 is formed in a substantiallytrapezoidal shape as seen from a lateral side. The contact line 60B isformed in a position which is lower by one step than that of eachcontact part 90 between a pair of longitudinal contact parts 90. Thetemperature sensor 35 is placed on the four contact parts 90. Eachcontact part 90 may be formed in the inclination line 60C.

With the sensor mounting structure 34 (biasing member 47) according tothe sixth embodiment as described hereinabove, the temperature sensor 35can be supported at four points. In this manner, backlash of thetemperature sensor 35 is restrained so as to be thereby able tostabilize a state in which the temperature sensor 35 is pressed againstthe positioning metal plate 40. The characterizing features of thebiasing member 47 described above may be applied to any one of thebiasing members 43 to 46 according to the second to fifth embodiments.

In addition, although the biasing member 47 described above included atotal of four contact parts 90 while two contact parts 90 are providedin one arched part 64, the present disclosure is not limitative thereto.It is sufficient if three or more contact parts 90 are provided. Inaddition, it is preferable that at least one or more contact parts 90 beprovided in one arched part 64. Namely, for example, three contact parts90 are disposed so as to form apexes of a triangle, and the temperaturesensor 35 can be thereby supported in a stable manner.

Although the biasing members 42 to 47 of the sensor mounting structure34 according to the first to sixth embodiments are made of a metallicwire rod and are formed in an annular shape, the present disclosure isnot limitative thereto. For example, in place of two arched parts 60 to64, one plate-shaped arched part (not shown) may be overhung between apair of engaging parts 50 to 52.

In addition, although in the biasing members 42 to 47 of the sensormounting structure 34 according to the first to sixth embodiments, therespective engaging parts 50 to 52 are bent in the substantialrectangular shape (substantial U-shape), the present disclosure is notlimitative thereto. For example, a pair of engaging parts may curve soas to form a substantially semi-cylindrical shape. Further, although inthe biasing members 42 to 47, the rear engaging parts 50 to 52 are cut,the front engaging part 50 may be cut without being limitative thereto.

Furthermore, although in the biasing members 42 to 47 of the sensormounting structure 34 according to the first to sixth embodiments, thepair of engaging parts 50 to 52 are formed in the same length in thevertical direction, the present disclosure is not limitative thereto.Although not shown, for example, either one of the pair of engagingparts 50 to 52 may be formed to be larger in length than the other one.In this manner, the biasing members 42 to 47 are easily mounted to theholding member 41, and the assembling work of the sensor mountingstructure 34 can be further easily carried out.

Still furthermore, although the description of the first to sixthembodiments is presented as to a case in which the sensor mountingstructure 34 is applied to mount the temperature sensor 35 of the fixingdevice 7, the present disclosure is not limitative thereto. For example,the sensor mounting structure 34 may be applied to mount an opticalsensor for detecting a conveyance failure of a sheet S in a conveyingpath 8 or a magnetic sensor or the like for detecting the amount oftoner in the development device 16. That is, the sensor mountingstructure 34 of the present disclosure is applicable to mounting of anarbitrary sensor.

Yet furthermore, although description of the first to sixth embodiments,as an example, is presented as to a case in which the present disclosureis applied to the color printer 1, the present disclosure may be appliedto a monochrome printer, a copying machine, a facsimile machine or amultifunction peripheral or the like, for example, without beinglimitative thereto.

The description of the foregoing embodiments presents an aspect in asensor mounting structure, a fixing device, and an image formingapparatus including the same, according to the present disclosure, thetechnical scope of the present disclosure is not limitative to theforegoing embodiments.

While the present disclosure has been described with reference to theparticular illustrative embodiments, it is not to be restricted by theembodiments. It is to be appreciated that those skilled in the art canchange or modify the embodiments without departing from the scope andspirit of the present disclosure.

1. A sensor mounting structure comprising: a positioning member as amounting reference of a sensor; a holding member provided to beattachable to and detachable from the positioning member so as to form aspace in which the sensor is disposed with respect to the positioningmember; and a biasing member including an arched part which is overhungbetween a pair of engaging parts engaging with the holding member,wherein the biasing member, while the holding member is attached to thepositioning member, elastically deforms the arched part that issandwiched between the holding member and the sensor that is disposed inthe space so as to bias the sensor to the positioning member.
 2. Thesensor mounting structure according to claim 1, wherein the holdingmember includes a pair of engaging protrusions which are formed whileextending in a direction in which the engaging protrusions are distantlyspaced from each other in a direction in which the arched part isoverhung, the biasing member is formed in an annular shape in whicheither one of the pair of engaging parts is cut and is made of a wirerod, the pair of engaging parts are formed in a shape curving or bendingso as to respectively overhang on the engaging protrusions, and thearched part is provided in a pair so as to be arranged in a direction inwhich the sensor is pressed and in a widthwise direction crossing theoverhanging direction.
 3. The sensor mounting structure according toclaim 2, wherein the engaging part having been cut is formed to benarrower in the widthwise direction than the engaging part that iscontinuous, and sandwiches the engaging protrusion while being overhungon the engaging protrusion.
 4. The sensor mounting structure accordingto claim 2, wherein the engaging part having been cut includes a pair ofcut ends extending in the widthwise direction so as to cross each other,the pair of cut ends incline so as to relatively bias the engagingprotrusion in the pressing direction while the engaging part having beencut is overhung on the engaging protrusion, the pair of arched partsincline to an inside in the widthwise direction so as to approach eachother towards the pressing direction, and the pair of arched parts,while the holding member is attached to the positioning member, arerelatively pressed against the sensor and then twist so as to furtherapproach each other to thereby decrease a biasing force of the pair ofcut ends with respect to the engaging protrusion.
 5. The sensor mountingstructure according to claim 4, wherein an inclination angle of saideach arched part is set in a range of 5 degrees or more and 10 degreesor less with respect to a vertical line extending vertically upward froma longitudinal line which is connected to the arched part.
 6. The sensormounting structure according to claim 1, wherein at least the archedpart includes an elastic part configured to elastically deform in anoverhanging direction.
 7. The sensor mounting structure according toclaim 6, wherein the elastic part is formed to meander in the widthwisedirection.
 8. The sensor mounting structure according to claim 6,wherein the elastic part has a downward protrusive shape.
 9. The sensormounting structure according to claim 6, wherein the elastic part isspirally formed.
 10. The sensor mounting structure according to claim 1,wherein the biasing member includes a pair of restraining partsconfigured to hold the sensor that is disposed on the arched part. 11.The sensor mounting structure according to claim 1, wherein the archedpart includes three or more contact parts which come into contact withthe sensor, and the three or more contact parts are disposed so thatlines connecting said each contact part constitute a plane.
 12. A fixingdevice comprising: a fixing member configured to heat, while rotating, atoner image on a medium; a pressing member configured to form, whilerotating, a nip with respect to the fixing member and then press themedium passing through the nip; and a sensor mounting structureaccording to claim 1, configured to mount the sensor configured todetect a temperature of the fixing member.
 13. An image formingapparatus comprising the fixing device according to claim 12.